The present invention relates to water aerosol or fog-generating systems, and more particularly, to a method of attaching an aerosol nozzle to a thin-walled pipe in such systems.
Water-aerosol or fog-generating systems allow one to better control the environment. It enables users to cool or humidify the air, as well as to control temperatures and minimize dust. Some systems administer chemical concentrates which may perform pest and disease control, and tissue culture and foliar feeding. The applications are limitless and each is due to one powerful environmental control resource--natural fog.
For purposes of the present application, aerosol or fog-generating systems basically comprise an atomizing nozzle, a pipe, and a compressor. The compressor introduces water under pressure through the piping and ultimately through a port in the atomizing nozzles. The nozzles are commonly equidistantly spaced at points along the piping. Each nozzle is affixed to the piping when positioned in a pilot hole drilled through the pipe wall. The aerosol or fog is commonly directed radially from the concentric axis of the piping.
The fog-generating industry is continuously searching for the most effective and economical material for constructing system piping. Finding the perfect balance between performance and cost has proven very difficult. Currently, two common piping materials are employed. The first is polyvinylchloride (PVC) and the second is brass.
In the case of PVC piping, a schedule 80 pipe is normally used. It provides sufficient strength and wall thickness for threading the walls of pilot holes so the nozzles can be affixed at each pilot hole. However, the PVC piping has been a difficult material to maintain due to inherent weaknesses in the manufacturer/extrusion process and the pipe's inability to handle hydraulic shock. Moreover, it deteriorates because of ultra-violet light and has the practical limitation of operating at pressures no greater than 600 pounds per square inch. PVC is, however, an ideal material from the standpoint of being non-corrosive, inexpensive, and easy to machine.
The brass piping is typically schedule 40, which has a reduced wall thickness but a higher strength than the typical PVC pipe. The brass piping has the advantage of being of high strength, high reliability, and thus has a higher operating pressure capacity. Schedule 40 brass piping is capable of operating at pressures much greater than 1000 pounds per square inch. The disadvantage of brass piping is that it is extremely costly and heavy. The great weight of brass piping results in higher transportation costs and in additional problems in suspending and supporting the system when the fog-generating system is installed.
Because of the drawbacks of using PVC or brass piping materials, the fog-generating industry has continuously sought for a thin-walled, but high strength, non-corrosive piping material. The material considered to be the most practical to obtain such goals is stainless steel. Stainless steel provides structural integrity sufficient to eliminate deterioration caused by hydraulic shock and ultra-violet light. It also has operating pressures at least as great as 1000 pounds per square inch while still having small thicknesses. Moreover, the use of stainless steel in a fog-generating system would provide the inherent rigidity to eliminate any elaborate support or suspension system which historically has been required by the heavy weight of brass piping.
As far as strength is concerned, it has been determined that a stainless steel pipe with a wall thickness as small as 0.035 inch is ideal. That is so because the weight is actually less than a PVC system, but its strength was far in excess. In fact, a stainless steel pipe with a 0.035 inch wall thickness has a pressure capacity well in excess of 1000 pounds per square inch. A difficulty arose because the pipe thickness was so small that there was not enough surface area for adequately threading the pilot hole for affixing the atomizing nozzle. Moreover, due to the curvature of tubular piping, the threads may be interrupted and thus they did not rigidly hold the atomizing nozzle to the piping. At a minimum, some piping material was not being used to hold the nozzle.
The industry routinely handled the problem of affixing the atomizing nozzle to the pipe by resorting to various welding techniques. Various types of female receptacle fittings were developed which could be welded into the pipe and which would then ultimately receive the atomizing nozzle. This process proved to be very costly in terms of both the additional fitting required and the welding process itself. Moreover, welding is a dirty process, causing internal oxidation which leaves residual contamination in the piping system. Residual contamination in a fog-generating system could render the system inoperable. A nozzle may have an orifice size as small as 0.008 inch. Therefore, the orifice must remain free from residual contamination to avoid repeated and frequent clogging or blocking. Moreover, such small orifice sizes require 10 micron filtration as well as elaborate water treatment and Ph control systems to provide reliable operation. Many in the industry have gone through the time and expense of putting filters on each individual nozzle to compensate for the inherent impurities which have plagued their fog-generating systems. Lastly, welding has been proven to be inherently unreliable because the welded areas have been plagued with joint failures.
Another problem associated with fog-generating systems which must be overcome by the present invention are the forces by inherent water hammer/hydraulic transient phenomena. These phenomena are caused by operation of high pressure pumps, high fluid velocities, and the frequent on/off cycling required. A nozzle and pipe assembly must be sufficiently rigid to withstand these sudden and high destructive forces.
Thus, there remains the need for the use of thin-walled piping, preferably made from a material like stainless steel, capable of withstanding an inexpensive but reliable method for affixing the atomizing nozzle to the pipe. Preferably, a method can be devised whereby welding would no longer be necessary and the piping systems would remain free from impurities.
The present invention increases the apparent thickness of the pipe so that it is capable of having enough threading to rigidly support existing atomizing nozzles within the piping wall. Moreover, the present invention decreases the chance of having interrupted threads by increasing the radius of curvature at the threaded portion of the piping about the pilot hole. The system requires no welding and thus remains relatively free from impurities. The techniques of the present invention allow the use of thin-walled piping made from alloys such as stainless steel which reduce the cost of present fog-generating systems. Also, the present invention includes a seal about the atomizer nozzle to prevent any dissipation of pressure between the threaded surfaces of the pipe and nozzle. Moreover, the seal absorbs inherent water hammer/hydraulic transient forces which are characteristic of fog-generating systems.
Other objects, features and advantages of the present invention will become apparent from the detailed description of the preferred embodiments which follows, when considered together with the attached figures and claims.